sys: add sys_getenv() (baresip#721)

include/re_sys.h

@@ -40,6 +40,7 @@ const char *sys_arch_get(void);
 const char *sys_os_get(void);
 const char *sys_libre_version_get(void);
 const char *sys_username(void);
+int sys_getenv(char **env, const char *name);
 int sys_coredump_set(bool enable);
 int sys_daemon(void);
 void sys_usleep(unsigned int us);

src/sys/sys.c

@@ -7,6 +7,7 @@
 #include <string.h>
 #include <re_types.h>
 #include <re_fmt.h>
+#include <re_mem.h>
 #include <re_sys.h>
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
@@ -21,6 +22,19 @@
 #include <sys/resource.h>
 #endif
 
+#ifdef WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <windows.h>
+#endif
+
+#ifdef WIN32
+enum {
+	MAX_ENVSZ = 32767
+};
+#endif
+
 
 /**
  * Get kernel name and version
@@ -180,3 +194,56 @@ int sys_coredump_set(bool enable)
 	return ENOSYS;
 #endif
 }
+
+
+/**
+ * Get an environment variable
+ *
+ * @param env   Pointer to destination env var
+ * @param name  Environment variable name
+ *
+ * @return 0 if success, otherwise errorcode
+ */
+int sys_getenv(char **env, const char *name)
+{
+	if (!env || !name)
+		return EINVAL;
+
+#ifdef WIN32
+	uint32_t rc    = 1;
+	uint32_t bufsz = rc;
+	char *buf;
+
+	buf = mem_zalloc(bufsz, NULL);
+	if (!buf)
+		return ENOMEM;
+
+	while (1) {
+		rc = GetEnvironmentVariableA(name, buf, bufsz);
+		if (!rc || rc == bufsz || rc > MAX_ENVSZ) {
+			mem_deref(buf);
+			return ENODATA;
+		}
+
+		/* success */
+		if (rc < bufsz) {
+			*env = buf;
+			return 0;
+		}
+
+		/* failed, getenv needs more space */
+		bufsz = rc;
+		buf   = mem_realloc(buf, bufsz);
+		if (!buf) {
+			mem_deref(buf);
+			return ENOMEM;
+		}
+	}
+#else
+	char *tmp = getenv(name);
+	if (!tmp)
+		return ENODATA;
+
+	return str_dup(env, tmp);
+#endif
+}

test/sys.c

@@ -204,3 +204,27 @@ int test_sys_fs_fopen(void)
 out:
 	return err;
 }
+
+
+int test_sys_getenv(void)
+{
+	int err = 0;
+	char *env = NULL;
+
+#ifdef WIN32
+	err = sys_getenv(&env, "HOMEPATH");
+#else
+	err = sys_getenv(&env, "HOME");
+#endif
+	TEST_ERR(err);
+
+	TEST_EQUALS(true, str_isset(env));
+	mem_deref(env);
+
+	err = sys_getenv(&env, "DOESNOTEXIST");
+	TEST_EQUALS(ENODATA, err);
+	err = 0;
+
+out:
+	return err;
+}

test/test.c

@@ -201,6 +201,7 @@ static const struct test tests[] = {
 	TEST(test_sys_fs_isdir),
 	TEST(test_sys_fs_isfile),
 	TEST(test_sys_fs_fopen),
+	TEST(test_sys_getenv),
 	TEST(test_tcp),
 	TEST(test_telev),
 #ifdef USE_TLS

test/test.h

@@ -320,6 +320,7 @@ int test_sys_rand(void);
 int test_sys_fs_isdir(void);
 int test_sys_fs_isfile(void);
 int test_sys_fs_fopen(void);
+int test_sys_getenv(void);
 int test_tcp(void);
 int test_telev(void);
 int test_thread(void);